Chicago



H. s. PARDEE CONTROL SYSTEM Rg. 18,033' 7 Sheets-Sheet 1 m oi Mw ow Ki J u H. s. PARDEE- April 7, 1931. CONTROL SYSTEM Re. 18,033

7 Sheets-Sheet 2 Original File d ot.1'9, 1929 H. S. PARDEE CONTROL SYSTEM Y 7 Sheets-Sheet 3 A ril 7, 1931.

Original Filed Oct. 19, .1929

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R Q v Q F mm m m mm. w. my W 0% Q% Qx N. n 7Q SQ \N m Q Q \J xi n E I QXIK H. S. PARDEE CONTROL SYSTEM Re. 18,033 Sheets-Sheet 4 April 7, 1931.

Original Filed Oct. 19, 1929- V il V W n nuu v H. sfPARDEE April 7, 1931. cpN'rRoL SYSTEM R 18,033

7 She ets-Sheet 5 Original. Filed Oct. 19, 1929 7H. s. PARD EE April 7, 1931. CONTROL SYSTEM Re. 18,033

'7 Sheets-Sheet 6 Original Filed 001;. 19, 1929 51b: 4/or Punp 3.9 or Pun! To .Sunp "rmvx 57' Z'a buMP TANK 57' rays am; P7

H. s. PARDEE April 7, 1931. CONTROL SYSTEM Re. 18,033 7 Sheetg-Sheet. I

Oiiginal Filed Oct. 19. 1929 UNITED, STATES PATENT OFF-ICE s. rm, or mwmm, rumors, assron'on r 101m 2.. nmcmnn, or cmcaoo, more CONTROL SYSTEM origlnal l iil 1,184,810, and December a, 1930, Serial No. 400,370, filed October 19, 1039. Application for reissue and February 9,1931. semi No. 514,638.

This invention relates to control systems,

and with regard to certain more specific features, to by aulic control systems. a 0.?

Amongthe seve rzfitls objects of the invention may be noted tlieprovision of a control system for operating the doors,'brakes and related parts of convegances such as street cars,

coaches, busses or t elike. v

Among other objects, this invention includes the one wherein the operation of the exit door is made independent of the motorman and whollyundercontrol of a leaving passenger, subject'fiyhlijito the single condition that the carbej subst-antiall'y at rest when said exit door is operated. In this connection, it is to be noted that the leaving passenger deprives the motorman of his control of the brake valve after the car has come to a stop, and operates to set said brake valve independently of the motorman, and in addition shuts'ofi the source of the propulsive power.

The invention has amon its further objects the provision .of a quic -acting, simple,

reliable and compact hydraulic control system having a minimum number of parts which, with small energy consumption, are

and exit doors at the front end and also an exit door at the rear end. The vehicles are also provided with at least one brake, prefer ably of the friction t contacting with some rotating element of t e vehicle.

Theinvention accordingly comprises the elements and combinations of elements, features of construction,and arrangements of parts which will be exemplified in the structure hereinafter described, and the scope of the application of which will be indicated in the folowing claims.

Drawings In the accompanying drawings in which are illustrated several of various possible embodiments of the invention,

Fig. 1 is a hydraulic and electric circuit diagram;

Fig. 2'is a fragmentary hydraulic circuit diagram, showing only certain filling circuit connections taken from Fi 1;

Fig. 3 is a fragmentary hydraulic circuit diagram, showing only certain relief circuit connections taken from Fig. '1;

Fig. 4 is a fragmentary hydraulic circuit diagram, showmg only a braking circuit connection taken from Fig. 1;

Fig. 5 is afragmentary hydraulic circuit diagram, showing only door opening circuit connections taken from Fig. 1;

Fig. 6 is a detail cross section of a door engine edalvalve;

Fig is a detail cross section of a brake pedal valve;

Fig. 8 illustrates a door operating engine and mechanism connecting the same with a oor;

Fi 9 illustrates the use ofa springbelow a bra 'e pedal;

Fig. 10 is a diagram illustrating-an alternative dead-man circuit;

Fig. 11 is a diagram illustrating an alternative brake system; Fig. 12 is a view showing certain reverslngwconnections from a pump.

ig. 13 is a diagram illustrating analternative door operating scheme; and,

Fig. 14 illustrates alternative brake pedal connections.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Introductory Although the invention herein is directed primarily to certain circuit conections and combinations, before said combinations can be understood there arises the need for descriptions of the various elements used.

Furthermore, it is believed that certain of said elements have' novelty per se. For.

these reasons a list of the various elements and their connections and uses will be set out, prior to describing theoperation of the invention as a whole.

Gar body As above forecast, the present invention is applicable to the so-called one man car or to cars manned by more than one operator. Cars of this type are well known as, for instance, the type in which there is provided entrance and exit doors at the front and an exit door at the rear and also the type in which there is a front entrance door and a rear exit door in which the passenger load circulates only from front to rear, there being no front exit. But the two types of cars described may comprise alternate operations on a car having a front entrance, front exit. and a rear exit and/or rear entrance. The point here desired to be made is that the system herein described may be varied in its application to various body constructions.

Dfioing and braking means M, W and A It is clear that the drive for the vehicle herein described may comprise the spur or worm gear type with brakes operating in connection with a drive shaft or the wheels. In Fig. 1 such a drive is diagrammatically illustrated as comprising a motor M driving a worm W, the latter meshing with a suitable worm gear A on an axle of the vehicle. As above indicated, the brakes may include shoes which are pressed directly against the wheels of the vehicle or may comprise other frictional means pressed against rotating parts such as discs associated with the drive shaft of the motor M or may comprise other optional methods of accomplishing braking. For purposes of description, the braking system herein is represented as comprising a system of brake cylinders B1 which operate friction brakes on the driving parts of the vehicle.

Automatic 'val'ves AV and RV Indicia AV represent an automatic valve for controlling the supply of fluid pressure to certain door engines. This valve has a diaphragm 33 connected to a valve head 35. ,On the upper side of the diaphragm is acompression spring 37 in a chamber connected to the suction side 39 of a pump PU (see line 6). 0n the lower side of the diaphragm is a chamber connected to the pressure side 41 of the pump PU (see lines 8, 7). This chamber also contains the valve head. The lower end of the valve chamber communicates with the pressure ports P of certain valves EP, XP and TV controlling said door engines (see lines 17, 14,16 and 15). When the pump is operating, excess pressure on the lower side of the diaphragm closes the valve 35 and shuts off the supply of fluid pressure to the door engine valves. When the pump is stationary, the suction and delive pressures quickly e ualize through a metering by-pass valve and. the valve AV opens under the action of the sp'rin 37, thus supplying pressure to the ports l to the door engine valves XP, EP, TV. 1

The valve RV com rises a relief valve arranged to short-circuit the delivery from the pump PU when the pressure in the tank PT exceeds a paedetlfrmined maximum.l 'ghils comprises a ia ra type, spring 09. e relief valve. .Eswifi be made clear, the pump runs during the time that the, vehicle is in motion and an average excess pumpage is assured if the pump is proportioned to provide suflicient quantity under all demands. When the maximum pressure is reached the pressure on the under side of the diaphragm 43 of valve RV lifts valve head 45 and permits the fluid delivered by the pressure side of the ump to short-circuit to the sump tank ST see lines 7, 8, 5, 3).

. The diaphragm spring 47 is of the compression type.

Foot controlled 'val'ves BP, EP, X P and TV The valve BP comprises a brake pedal valve, the details of which are shown in Fig. 7. This valve comprises a port P leading to an internal poppet valve HS4 which is closed by a spring HS5, as well as by fluid hand pressure exerted by the operator of thevehicle. On this stem HS7 is located a solid piston HS8 and below the latter, is located an axially perforated piston valve HS6.

In the position shown in Fig 7 the stem is 3 fully depressed and pushes against the end of the stem of the poppet valve and opens the latter and permits fluid pressure to pass to the under side of the solid piston HSS, thus tending to raise it and the 'stem. At the same time. pressure passes through HS6 to the port B and thence to the brake cylinders. Thus the pressure on the under side of the solid piston HSB tending toraise the stem is in proportion to the pressure on the brake cylinders. If the pressure exerted on the stem by the operator is reduced the valve stem rises and the piston valve HS6 eventually cuts of the pressure supply to the brakes.

Further reduetlon of the pressure on the stem causes it to rise still further and the lower edge of the solid iston HS8 uncovers the port to the exhaust and ressure on the brake line is reduced as the piston rises or is kept in exhausting position. At the same time the pressure on the under side of the solid piston is alwa s proportional to the pressure on the bra e line. The distances maybe adjusted so that there'is an appreciable lap between the pressure supplying and exhausting positions. When the operator removes ressure on the stem entirely, the stem rises, a lowing the poppet-valve to rise also, and the latter finally closes and shuts off with a tight seal the pressure supply to the piston va ve. Thus the piston valve HS6 is relieved of the function of sealing against pressure, the poppet valve KS4 assuming this function. It is to be noted that the poppet valve seals tighter as the pressure builds up; whereas a piston valve is always subject to some leakage. Such leakage has been here prevented.

Above the solid piston is a chamber communicatin with port C which leads to the magnetica ly controlled valve FF. When fluid pressure is admitted to port C from the sup ly tank, the pressure on the upper side of t e solid piston depresses it and thus supplies pressure to the brake system independ-' ently of the operator. The operation will be further clarified in the description of operation of the apparatus, taken as a whole.

The valve P (Fig. 6) is also a pedal valve which, like the valve BP is adapted to be manually depressed by the operator. Its

- purpose is to control the opening of a front entrance door by means" of a suitable door engine FED (Fig. 1). The valve EP per se is detailed in Fig. 6 and comprises a threeway valve with a pressure supply port P, an exhaust port S leading to the sump tank ST (see lines 20, 13, 3) and a deliveryport D leading to the door engine FED (see line 24). The stem of the poppet valve H84 therein pilots in the operating stem HS13 and when the latter is depressed, the poppet is opened, thereby communicating fluidv pressure to the door engine FED by way of port D.. The piston valve HS6'is perforated axially so that the pressure on the two sides is balanced. In the position'shown the stem is fully depressed and the pressure line is open to the delivery port D. As the valve stem is raised the poppet valve HS4 is first closed, making a tight seal. Next the exhaust port S is put in communication with the port D and the fluid in the door engine line exhaust to the sump through port S. The upper part of the valve stem passes through two packing rings HSlO set in cups and between the two is a space 71 connected by a drilled hole 73 with the exhaust port. Therefore if any fluid passes the lowest packing ring it will be drained to the exhaust line before it can reach the upper packing and thus no fluid can escape from the stem.

It will be noted in connection with the descriptions of valves EP and BP of Figs. 6 and 7 respectively, that corresponding reference characters indicate parts having corresponding shapes and functions.

The valve XP (Fig. 1) comprises another dal valve similar to valve EP and has for its purpose the operating of the front exit door engine FXD,similar to the manner in which the valve EP operates the front entrance door engine FED. The two front door pedals XP and EP are juxtaposed so that either or both may be depressed simultaneously with the brake pedal; or the brake pedal may be de ressed alone.

The treadle va ve TV is a valve also similar to the valves EP and XP, except that the stem thereof is connected to a treadle T and and supplies pressure to the rear door engine and opens the'door in the same way as EP opens the front entrance door. When both treadle and step are in raised position valve TV is set to 0 en the line from the door engine to the ex aust and permit the door to close itself by action of its 'return spring hinges which forces the fluid from the door engine when the door is closing.

Hand controlled eal'ves HB and FV At HE is illustrated a hand brake valve which may comprise an ordinaxI'y fourway valve of the ta ered plug type. n the position shown in ig. 1 it is in normal position. When the handle is put in the position shown bythe dotted lines the pressure tank is put into direct communication with the brake cylinders and all of the pedal valves and door mechanisms are out of service. HB will usually be placed in thevout of service position when the car is out of service or left standing for a time. If the car is left standing with the brakes applied by the brake valve BP, due to o ening of the dead-man circuit and release 0 the magnetically operated valve FF, the pressure will slowly but gradually leak past the iston in valve BP, and finally all of the flui in the pressure tank PT will pass to the sump tank ST. But valve HB can be made inherently tight and hence the pressure will be maintained indefinitely without any leakage when valve HE is used The valve.

to hold the brakes. Valve HB also serves as an auxiliary valve for use incase of accident or damage to the other valves and/or mechalines in Fig. 2 the pressure tank PT is connected to the air valve AC and a hand pump HP.

Slip 'val've N V This valve comprises an adjustably throttling, by-pass located between the suction and delivery lines of the pump PU. It augments any pressure equalizing leakage which may Magnet valve FF, M V

The magnet valve FF, MV is energized by a low voltage dead-man circuit which will be described hereinafter. It includes a pair of contacts LS which are opened when the magnet is-deenergized and open the line circuit breaker su plying propulsion power. The magnet MVE preferably of the solenoid type, is connected by a leverto the rotating stem of a three-way valve FF. When the magnet is energized, the port P of this valve FF leading from the pressure system, is shut off and the port C leading to the control chamber of the brake pedal valve BP is connected to the exhaust port S leading to the sump tank ST. When the ma net valve is deenergized the pressure port is connected to the control port C and the exhaust port S is closed. This communicates pressure to the chamber C of the brakevalve BP and acts to set the brakes as described inconnection with the description of the brake pedal valve BP.

Door engines FED, FXD and RXD .haust line is connected to the door engine thesprings cause the door linkage to return the piston of the engine and force out the fluid to the exhaust. This flow may be aided by gravity when the door engine is placed higher than the sump tank ST.

Indicia FXD and RXD represent door engines for the front exit door and rear exit doors respectively, said engines being similar in form and operation to said described door engine FED.

In Fig. 8 is illustrated the connection between a door engine and its door, including spring-hinge return.

Pressure is admitted to a chamber WC of i the .door engine between the inside of the cylinder 101 and the outside of bellows 103. This causes the rod R1) to move outwardly to open the door against action of a door spring DS on a door shaft SH which turns in a ing positions and the rod RD into working cylinder WC. The check valve CK seats, causing all of the fluid to pass through the annular space around valve VT. The valve VT can be so shaped as to regulate the angular velocity of the door closing at any point and prevent slamming or too great a speed at any point in its travel. K is a cock for venting air from the system when it is initially filled with liquid. It is important that no air be trapped in the system if it be h draulic; otherwise the engines will not properly responsive to their control valves.

The bellows 103 are preferably of metal.

spun into the shape of cylinders with corrugated cylindrical surfaces to provide for expansion and contraction in axial directions. Or the bellows may be made up of se arate discs soldered or welded together to' orm a bellows structure. Both methods are in common use. Preferably the pressure is exerted on the outside of the bellows as this sets up forces analogous to a spring in tension and hence prevents buckling. If the pressure is exerted on the inside of the bellows, the forces set up are analogous to a spring in compression with consequent tendency to buckle,

necessitating use of guides and the like which (a) No stufling box is necessary for the rod. I

(b) No piston rings or cups are needed.

(If) The system is closed with absolutely no lea age. Leakage in a hydraulic system is a vital factor because if it be not caught and returned to the sump it will escape from the system and eventually render the braking and door meansinoperative. When the brake or door engine cylinder .are located below the sump tank it becomes awkward to collect leakage and return it to the sump. From a practical standpoint a closed system using bellows or the equivalent for cylinders is desirable, unless leakage can readily be returned by gravity to the tank.

Rear treadle and step T and S1 The letter ,T indicates a preferably small, hinged platform or treadle placed inside-of the rear door exit, arranged so that a passenger upon leaving the car by this door will manually step on the treadle and depress it slightly against the action of, compression rings 55 therebeneath. The treadle is artlculated kinematically with a step S1 so that both work in unison in actuating a switch TS and the valve TV; or, the platform treadle and the step may independently operate the switch and valve. The former method is indicated in Fig.1.

The ste S1 is placed outside or inside of the rear oor of the vehicle. The tread of this step S1 is permitted to assume slight downward movement of its outer edge when alighted upon by a passenger and this movement is utilized to actuate the treadle valve TV and the treadle switch TS, movement being effected through the treadle T by way of linkage 57. The step S1 is maintained in the slightly raised position by suitable the liquid level although not always so.

springs 59 therebeneath which are-overcome by the weight of a passenger on the step. When the passenger leaves the car and alights from the step the springs raise it and actuate switch TS and valve TV. It is to be understood that this is preferably not a folding step, the vertical movement being restricted to approximately one quarter inch.

Hydraulic pump PU Check valves 0, AU and OR The check valves used herein comprise the parts indicated by letters 0, AC and GR in Fig. 1. These valves require no further de-' scription, inasmuch as their construction is well known. They permit flow in one direction (to be set out) but not in a reverse direction.

Filter AF The air filter AF is provided for maintaining the purity of the air that passes into a sump tank ST, to be described. This filter AF also functions as an air vent when liquid enters the tank ST so as to displace the air therein. The filter AF is connected by a line '4 with the sump ST in such manner that its elevation is above the liquid in the sump. The elevation of the opening of line 4 in the sump ST is also normally above Aum'lz'afies BY, DU, FP, G, HP and HV The device BY is a battery, preferably of low voltage, for operating the magnet MV and certain si al lights.

The device side of the sump tankfor draining the same; and also for drawing off any water which may condense or dirt which may collect in the sump tank ST.

FP comprises a filling plug for filling the sump tank with fluid. It consists of a funnel and stop cock.

G is a. gauge for indicating the pressure in the pressure tank.

Indicia HP represent a hand pump for filling the .ressure tank PT from the .sump tank ST w en the equipment is initially put into service. This pump has the inlet and outlet check valves 59 and 61 at intake and delivery respectively. The pump HP is not always essential, nor the charging means through 63 and AC, because the car could be run for a distance without brake pressure until the regular pump PU had pumped the fluid from ST to PT; but. it is usually desirable to start with suificient brake pressure immediately available. The hand pump also serves as an emergency supply in case of accident to the pump PU. It will be seen from the above that 'means for placing air under pressure in the pressure tank may comprise temporarily operating either of the liquid pumps PU or HP so as to bring the pressure up from an initial atmospheric pressure to the operating pressure; or using the charging means AC, 63.

HV is a holding valve, used in connection with the front door engine FED, arranged so that it may be closed to keep the door C is a drain cock on the under I from closing, when desired, with the door I pedal released.

' Tanks PT and ST The tank PT comprises a pressure tank designed to withstand the air pressure used and to be air, oil and water tight, for example the tank pressure may be 100 pounds per square inch.

The sump tank indicated by indicia ST, is under atmospheric pressure and preferably placed at the lowest part of the system to receive the drain from thedoor engine and brake cylinders. It is provided with the drain cock DC and an air vent leading from the top of the tank to the filter AF which filters the air as it passes in and out of the tank as it is alternately partially filled and emptied. The size of this tank is preferably such that when full it .will hold such a quantity that when substantially all of its contents is pumped into tank PT, it will raise the pressure in tank PT from mini- Diaphragm Makes sL'aMz ms The switch SL comprises contacts 49 in a battery-stoplight circuit adapted to be operated by movement of a diaphragm 51. The chamber on one sideof the diaphragm 51 is connected to receive pressure from a brake valve BP (see lines 25 and 29) before lighting the stoplight w indicate stop thus warning the drivers of vehicles following that the car herein described is about to slow down or stop.

The switch RS is of similar type-but wired into what is known in the art as a dead-man control circuit, said switch RS being arranged to open the circuit and thereby set the bra es when the rear door is open. The upper side of the diaphragm 53 is connected to the pressure of a su ply tank PT (see lines 32, 9, 26, 1), while the other side of the diahragm is connected to a rear door engine 1 XD (see lines 22 and 21). When the pipe 22 is not under pressure, that is, when the rear door engine is in door closing position the diaphragm of switch RS will act to close the contacts in the dead-man circuit because of the action of the supply pressure in pipe 32. When the rear door engine is under pressure and the door is opening or being held open by the engine, then substantially equal pres sure will be applied to the other-side of the diaphragm of S and thus counteract the opposing pressure from PT. The spring 54 will then act to open the contacts. As soon as the rear door engine line is connected to its exhaust, the pressure will again preponderate on the upper side of the diaphragm, and when the differential pressure has reached a predetermined amount, the diaphragm of valve RS will function to close the contacts. The action of the valve BS is thus dependent upon the pressure difierential existing between the supply tank and the r engine and not upon the absolute pressure existing in the system or the supply tank PT. If the difierential adjustment of the instrument RS be made small a 'very small time interval will take place between theinstant when the door starts to close and the brakes are released and power applied for propulsion.

Switches Bs, 0H, Fs, R and TS -An lectr'cb k-u b ki 'thBS' I e l ac p m ng SW1 c 1s accurately illustrated in Fig. 1 and comlocated at the rear end of the vehicle, or at any other desired point, arranged to 0 en the circuit controlling the magnet valve F MV, andthus supply fluid ressure to the port C of the brake valve B which applies the brakes. At the same time the supply of motive power to the vehicle is cut ofi by contacts LS on ma et MV.'

A switch C is located on the handle of the motormans controller re lating the sup-' ply of propulsion power. is is called a dead-man switch because-it opens when the operator, as in death, lets go of the handle. 0 ening of this switch releases the magnet MR7 and valve FF so as to set the brakes and out OK the supply of power by means of contion the dead-man circuit is open. This neutral position is the position of the handle 1 when the car is out of service and is usually maintained and locked with a key. This arrangement insures that the brakes are set and the car impossible to operate while thuslocked.

The switch TS is operated by depression of the treadle or rear step so as to close a circuit from the batte through a signal lamp RDL in front of t e motorman to indicate when a passenger is standing upon the treadle or step. In parallel with this signal lamp is a lamp SW located in the riser under the treadle to illuminate the step whenever it is about to be occupied.

Lamps RDL and PM L The signal lamp RDL, as indicated in connection with the description of the switch TS, is in circuit with said switch TS so that when the switch TS is closed by depression of treadle or rear step, said signal lamp RDL (near the motorman) will indicate when a passenger is on the treadle or step.

The lamp DMLcomprises a signal in the dead-man circuit which burns whenever said circuit is closed and in running condition and indicates to the motorman that the brakes are not set and that the line circuit breaker is not opened by action of the dead-man circuit.

I Prefmed connections (iageneral) 5 Pneumatic and electrical connections are ments concerning diiferent phases of the op eration.

Operation (filling circuit connection, Fig. 2)

1') an air hose 63, connected with a source of compressed air, is connected to the air check valve AC and air is passed to the ressure tank PT b way of line 1. When t e pressure, as in icated on the auge G, reaches the minimum at which the oorengmes and the brake cylinders will operate pro erly the .air hose 63 is removed. Next the- 'ydraulic fluid, preferably a suitable grade of oil, is ut into the sum tank ST through the fillmg plug FP an line 3. As oil enters this tank it forces out the contained air through the vent 4 and air filter AF. When the tank ST overflows through filter AF the filling plug FP is closed. Then-the hand pump HP is operated and most, but not all, of the fluid in tank ST is pumped (through lines 3, 2, 1) into the pressure tank PT. The sizes of the tanks PT and ST being in the correct propprtion, the pressurein tank PT will now near the maximum pressure suitable for operating the brakes and door engines. The hand pump HP is stopped and valve FV turned to its normal position indicated by the solid lines in Fig. Operation (relief circuit connection, F 2'9. 3)

When the car is put in motion the pump PU starts to pump oil, drawing from tank ST through pipe 3 and check valve 0 to the suction side 39 of the pump and thence delivers under pressure through pipes 7, 10, 9, 26 and 1 to the pressure tank PT. However, branching from this run 7, 10, 9, 26 and 1 is the pipe 8 leading to the relief valve RV which 1s set to open under the maximum pressure and by-pass the output of the pump through lines 5 and 3 back to the sump tank ST. Thus the building up of more than the predetermined pressure in tank PT is-prevented, even though the pump runs continuously. When, as will be part-icularized hereinafter, fluid is withdrawn from the tank PT and the pressure therein and lines connected therewith falls to the predetermined minimum at which valve RV is set to close, then the output of the pump passes to the tank PT or directly to the devices which may happen to be using the fluid at the time.

Operation (braking circ'wit connection,

Fig. 4)

- As above descri 12 to the brake cylinders B1. .The piston rods and the linkages o erated from these cylinders move the bra 0 shoes into frictional contact with the wheels, the axle, or pgopeller shaft of the vehicle, as the case ma In releasing the brakes the pedal of P is raised. This cuts ofi port P and connects ort B to port S. Suitable springs in the rake cylinders move-the brake shoes out of y frictional contact and force the fluid back throu h line 12, valve HB and line 25, ports B to ,gandlthrouglr-pipesm and 3 to the sump alvezBP, as described above,lis'arran d sothat the ressure de-.

livered tothe: rake "cylinders s adaptable adjustment from zero to max1mum,-

to an accor 'ng to the amount of pressure applied on the pedal and the reaction tending to oppose the movement'of the pedal downwardsis always proportionaltothe pressure existing in the brake line i. e., the amount of brake pressure applied depends upon the amount of foot pressure exerted by the operator on the pedal.

When the brake pedal is connected directto the valve stem, as illustrated in Fig. 1,

l the movement can be made as small as desirable, down practically to the amount of lap of piston valve over pressure and exhaust ports. A very slight movement beyond this will build up or release pressure. The operator then merely varies his foot pressure, the pedal remaining almost but not quite stationary. If, in order to simulate automobileoperation, it is desired to add appreciable movement-to the pedal it is only necessary to insert a compressionspring 129 between the pedal and the valve stem (see Fig. 9). The stress in the spring then reacts on the pedal always in exact proportion to the pressure existing in the brake line.

Operation (door controlling circuit, Fig. 5

depresses one or both of the pedals of valves EP or XP simultaneously with the pedal of valve BP. This puts in communication the port P of the door valve with port D. However, nothing happens to the doors while the car is in motion, because there is no pressure on the lines leading to ports P. These lines are controlled b the automatic valve AV. d AV is the diaphragm valve, spring loaded on the u per side and connected to the suction side 0 the ump by line 6. The under side of this diap ragm is connected to the pressure side of the pump through pipes 8 and 7 ,"and to the pressure tank PT through lines 8, 10, 9, valves HB,

FV and line 1. When the pump is running the pressure difference. on. the two sides of the diaphragm is equal to the pressure difference at the pump. This closes the valve connected to the under side of the diaphragm. When the. pump is substantially stopped, the predetermined leakage through the metering valve NV quickly builds up a pressure on the suction line being held by the check valve 0, and this pressure communicates through pipe 6 to the upper side of the diaphragm of AV, equalizing the pressure on the lower side, which, together with the action of the light spring 37 pushes the valve disc 35 down and open. Pressure is then admitted to the lines leading to the valves controlling the door engines and if any or all of these are set for door opening, fluid will flow through the valve to the door engine cylinder and with suitable pistons and crank link cause the door to open against the opposition of its return springs. When the door valve pedal is released the port D is connected with port S and the springs on the door hinges cause the istons to force the fluid out of the engine and back through the valve and pipes 19 and/or 20 and/or 18 to pipe 3 and tank ST. It is to be noted that according to the amount of inherent hydraulic slippage in the pump PU, the valve AV can be adjusted to open slightly before the pump wholly stops and thus the doors can be opened, if desired, slightly before the car has come to an absolute stop. This feature conserves time in length of stops. If desired the operator may depress both of the valves XP and EP together with the brake pedal and thus open both front doors when or as the car stops; or, he may depress the brake pedal without the door pedals and thus come to a step without opening the doors. Suitable juxtaposition of the pedals XP, BP and EP as shown, permits this selective and/or simultaneous action.

In one-man cars it is highly desirable to circulate the load in through the front entrance and out through the rear exit. Thus passengers desiring to leave the car go to the rear and stand on the treadle T.

The movement of the treadle putsport P of valve TV in communication with port D thereof. It is "to be remembered that the valve TV is operated'by the treadle in substantially the same way that the motorman operates the valves EP and/or XP. When the car comes to a stop, and thismay be for any reason such as cutting off the source of power, or obstructions on the track or road, the automatic valve AV admits hydraulic pressure by way of line 15 to the valve TV and through port P to port D and thence to the door engine line 21. This causes the door to open. As the passenger alights he steps upon the step S1 which is connected to perform the same functions as the treadle T and this holds the door open until both ,step S1, these members rise to their normally raised positions due to the springs thereunder.

Operation (safety cirwits, Fig. 1)

The movement of the treadle T when a as senger is thereon also closes the switch T in a signal circuit including the battery BY and the signal lamp RDL. The lamp RDL is located near the operator of the vehicle and he is therefore notified to stop the car at the next stopping point. It is to be understood that the usual push buttons and buzzers or mechanical signals may be used in addition to this treadle signal, or instead of the treadle signa In connection of the operation of the treadle valve TV, it is to be noted that when pressure is admitted to the rear door line 21 it also communicates by way of line 22 with the diaphragm chamber of the diaphragm-operated switch BS. The resulting diaphragm movecludes the magnet valve FF, MV. The magnet MV opens the three-way-valve FF per se, thus admitting pressure to port C of the brake valve BP by way of line 27 and causes said. valve BP to function as if depressed to set the brakes (see Figs. 1 and 6) Pressure is admitted to the three-way valve FF from line 10, the said positioning of the valve FF connect-- ing ports P and C thereof (see Fig. 1);

, Simultaneously with the above operation, the magnet MV opens contacts LS which control power delivery to the vehicle. For instance, in the case of a gas engine drive, the contacts LS may be in the ignition circuit; and in the case of an electric motor drive the contacts LS may control an opening coil of a line circuit breaker. Thus the event of a'passenger standing on the treadle T lights the operator signal lamp and as the car comes to a stop opens the rear door, shuts off the power and sets the brakes. In connection of the brake setting, it is to be noted that the operators brake setting is not interfered with, be-

'ment opens the dead-man circuit which incause the passenger-controlled brake setting door opening and braking receive their energy. But after the car has stopped, the operators brake operation is dominated by that of a passenger standing on either treadle or step.

When the treadle T and step S1 are both free, the reverse operation takes place, the dead-man circuit is restored, the brakes released, the power supply re-established and the signal light RDL turned off.

In connection with the door operation, it will be noted that the single-actlng engines for opening the same and the spring means for closing the same makes it possible to push thedoors open from the outside against the actionof the return springs for the same and it is also ossible for a passenger on the inside to open't e door by grasping a handle without the aid of the door engine. This feature is valuable in making emergency entrance or exit should the motorman become incapacitated. Likewise, it is possible to close the door by pushing it even though the engine is tending to open it.

Another function of the dead-man circuit is to shut off the sources of propulsive power and apply the brakes to stop the car independently of the motorman, should he become incapacitated or for any reason let go the switch maintaining this circuit. It coniprises a push button switch OH in the motormanscontroller handle which button opens the dead-man 1 circuit when the handle is let go. This switch is shunted by a foot operated switch F S which can be held closed by footpressure when the motorman Wishes to have both hands free. From the switch CH the dead-man circuit passesalso through another switch R associated with the conventional reverser handle.

When the latter is in either forward or backing position the dead-man switch at that point is closed. When the reverser is in neutral position the dead-man circuit is open. When the car is out of service it is usual to lock the reverser in neutral position with a key.

The diaphragm-operated switch SL operated by line 39 leading from the lines 12, 25 (associated with the brake cylinders B1) is adapted to close and light the stop light SS whenever there is pressure in thebrake cylinder lines 12, 25.

It will be appreciated that it is often desirable to back one-man cars around a Y or backward'through a switch and this movement must be controlled from the rear end. A normally open backing switch controller is usually positioned in the rear end. At'the front end of the car the motorman sets his reverser in backing position and the controller on about the second running position. He then applies a special clamp to the controller handle which holds itinthat place and holds the dead-man button closed down. Going to the rear he operates the backing switch controller handle in backin In order to brake from this position Iprovide, in connection with the backing switch, the pair of contacts BS in series with the deadman circuit so arranged that they are normall closed but are opened when the backing han 1e is moved negatively past the off position and awav from its driving positions. This permits braking and stopping of the car from the rear.

In backing the car the pump will operate in reverse direction (if it is a reversible pump) and in order to prevent building up excess pressure on the side which is normall suction I provide acheck valve CR whic the car.

relieves said excess pressure to the other side of the pump while backing.

In the case of reversible or so-called double end cars in which the pump may run continuously in either direction, I provide in connection with the pump a system of four check valves 115 as shown in Fig. 12. The arrows indicate the direction in which the check valves'permit the fluid to flow from points of high to low pressure. The pressure line PL then is always a delivery line and the suction line Z always conveys fluid to the pump. In this modification the check valve GR. is unnecessary.

Alternative forms In Fig. 10 is illustrated an alternative brake and door piping system including an alternative dead-man valve.

In this modification the dead-man valve DMC includes a solenoid therein and operates to transmit fluid pressure directly from the tank PT (see line 117) to the port P of said valve DMO and thence to the port B of the valve DMC (when the valve is de-energized) and thence to the brake cylinder B1.

' Vhen the valve DMO is again energized, port B connects. with port R and thence to port B of the brake pedal (in released position) to ports and thence to the tank ST. This re? leases the brakes.

of valve DMO and thence to port B to the brake cylinder B1. Hence either of valves DMC or HP can set the brakes independently but both must be set in release positions in order to release the brakes.

. The treadle valve here acts directly (hydraulically) on the brake pedal valve BP, in-

by means of an electric stead of lndirectl circuit including t e pressure switch RS and magnet valve MV, as shown in Fig. 1.

In Fig. 11 is shown another modified brake system in which the treadle valve TV works a separate brake cylinder B2 independent of the cylinder B1 operated by the motorman. It is also to be noted that the automatic valve AV has atmospheric'pressure on the underside of the diaphragm and a check valve on the pressure side of the pump. I When the pump stops, pressure on the delivery side thereof drops to that of the suction line. This permits pressure to pass from pressure tank PT to the treadle valve TV by way of the automatic valve AV so that when the treadleis operated the rear door engine RXD and the brake cylinders B1 will function.

In both of the modifications a signal circuit' 119 is adapted to be closed upon the pressure of the treadle so as to light a signal lamp 121. I

In Fig. 13 is shown an alternative scheme for closing the doors by pressure and permitting spring opening of the same. In thisconstruction a valve VV is used beneath the treadle and is adapted to be operated thereby. When treadle is raised pressure from tank PT goes directly to door en ine to hold the door closed a inst action 0 springs which tend to open 001s in this case. Stepping on treadle cuts or't' pressure and connects the door en 'ne line to the automatic diaphragm valve A 2, which, however, is closed as long as the car is runnin and pressure on the up er side exceeds t at on the lower side.

en .the car stops, the valve AV2 opens and permits the door en 'ne to exhaust its fluid to the sump tank an the door springs open.

In Fi 14 is shown an alternative system in whic a brake pedal BP2 is formed at the end of a. spring-held link 131 and a rod 133 connects said link.131 with a diaphragm 135. The pedal BP2 in the position shown, connects the brake cylinder to the sum tank. Depressing pedal BP2 connects bra e cylinder B1 to the pressure line, this being done b the linka e connection 137 with valve F2. The iaphragm 135 provides reaction to the pedal proportional to the pressure reachin the brake line. B plac- 1ng ports S, B, close enough toget er the amount of motion of the pedal can be as little as desired.

The magnet MV2 when energized holds up the pedal in release position; when deenergized it allows the spring to pull pedal down and apply the brakes.

If desired, b means of a lost motion link the pedal itsel may be caused to be unmoved by MV2.

Flm'd Although it ispossible; to apply the present invention to a pneumatic system, it is g l'fferable that a hydraulic system be used.

e hydraulic fluid to be used in the present system comprises preferably ,a' liquid relatively non-expansive and non-compressible as com ared with ases such as air. It should selected with a viscosity reasonably constant at the various operating temperatures; it should not corrode metal and should have a low enough vapor tension so as not to create an appreciable vapor pressure at theo erating temperatures. It should not deteriorate with time or use. It will be seen from the above that fluids such as are.

now. known for hydraulic braking systems may be used, or oi or the like.

For when a valve in a liquid pressure line is closed the energy flow is,

stopped. When a compressed air line is closed ofl the flow 'of energy at the delivery end of the pipe line may not cease, because some uncontrolled energy due to the pressure of the expansible medium in the pipe line has passed the valve and this energy can be governed only by complex arrangements and elaborate counteracting means. Thus it will be seen that the energy of a hydraulic system is simply and directly controllable.

Power consumption in the hydraulic system is much less than in the pneumatic system wherein the air or the like must be used non-expansively, as in direct reciprocatin engines exhausting at full pressure. Wit the hydraulic system there is not only a saving of energy, but what is often more important in a vehicle, there is a great savingin the weight, bulk and cost of compressing equipment. In a hydraulic pump and motor the only loss is in friction, in the pneumatic system practically all of the work of com ressing the air is wasted and only the equivalent of the work of ejecting the fully compressed air from the compressor cylinder is used in the engines or brake cylinders.

Pneumatic systems require heavy and bulky cooling systenis, comprising usually a coil of pipes to dissipate the ener of compression. Nothing of this nature 1s required in hydraulic systems.

In pneumatic s stems moisture is naturally condensed w en the compressed air is cooled. This gives much trouble in obstructing the system when .it freezes.

Li uid is much easier to retain in a system t an compressed air. -Much of the usual air compressor capacity is used in making up leakage in the piping, valves and cylinder packing.

A given amount of energy can be passed.

through a pipe and valve ports much quicker with a 1i uid than with air used non-expansively. his results in faster operation in applying and releasing brakes and in opening an closing doors, which com rises an important element in z'speedy an eflicient operation of conveyances.

(2) The motorman-is in full control of the brakes at all times when the car is in full motion, assuming that he is attending "to his duty. His operation thereon is not interfered with by the gsitioning of passengers on the treadle. ence his acqulred skill in pro erly bringing the car to a stop is not inter ered with. The reason for this is that the brakes are not operated from the controlling valve TV until-the car has reached an optimum lows eed or stop at which the motorman woul b obliged vto completely set his brakes anyway. Thiswill be seen to be true if it be'noted that the automatic valveAV normally prevents pump Y the diflerential pressure on the two sides of the diaphragm of valve AV. The valve NV functions in this way inasmuch as it 1s set to by-pass at low pump speeds, not unlike the by-pass action had due to slip past the piston of any pump at low speeds.

After the automatic valve AV opens, pressure is transmitted from line 8 to line 15. Thus all of the valves TV, XP and EP are potentially supplied with pressure inasmuch as they all draw from the line 15.

(3) From the above it will be seen that neither the motorman himself nor anyone else can, by means of the hydraulic system, open any of the doors RXD, FXD or FED, until the car has reached a substantial -stop, the reason again being that there is no pressure available at the valves TV, XP and EP until the automaticvalve AV permits it to become available at a very low vehicle speed.

(4) The motormans brake valve cannot be set to release if a passenger is standing on the treadle with the door open. The treadle valve acts on the motormans valve, taking the control of same entirely away from him and moving the motormans valve to braking position regardless of his own acts. How ever, braking is under control of the motorman, even though a passenger is on the treadle, as long as the car is moving at an appreciable speed.

(5) When the car is stopped,'either the motorman or the passenger on the-treadle can set the brakes independently of the other.

Both must have their brake setting devices in release position in order to release the brakes. Neither can release without consent of the other.

(6) The door opening means is operable whenever the car is stationary, even though the brakes are not set. After the car is stationary the setting of the brakes is coincident with the opening of the door. v In some prior systems the doors cannot be opened until the brakes are set which means a loss of time in making stops. 7 v

' (7 Economy of equipment is efiec'ted b providing the dead-man control circuit wit the dead-man switch and a control-operated diaphragm switch, whereby the same valve FF, MV and connected lines, such as 10, 27, 28 serve for emergency braking and for passenger-positioned-control braking. At the same time the emergency braking can take place at any speed; whereas the passengercontrolled braking occurs only near zero velocity. I

(8) The treadle does not prevent'the door from being closed manually. The doors are never looked open nor locked shut.

(9) The doors can be opened from the outside by pushing which com rises a valuable feature, inasmuch as it enab es entrance to be efl'ected from the outside should the motorman be incapacitated or a panic exist within the car.

To recapitulate, this invention comprises a control system in which a pump operates while the vehicle is in motion. The pump circulates fluid through a system and provides a difierential pressure therein. In the system is located means for making use of said diflerential pressure and also of non-difierential pressure which occurs when the pump is not operating, as when the vehicle is stationary, the slip meansassociated with the pump providing the non-difierential pressure.

The system operates so that the pump with draws fluid from the sump'tank and delivers it to the pressure tank, except such portions I of the fluid as pass through the by-pass from the pump delivery line to the pump inlet line when the valve in the by-pass relieves at the pre-determined ressure.

It will be un erstood that the motorman may set his brakes under the difl'erential pressure conditions and that under the equalizing pressure conditions, passenger-operated means may and does set the brakes.

I In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructions without departing from the scope of the invention, it isintended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a vehicle control circuit,-a pressure tank, a sump tank, means for lacing liquid in said sump tank, and means or placin air under pressure in said pressure tank am? for pumping liquid from said sump tank into said pressure tank'to further buildup the pressure therein.

,2. In a vehicle control system, devices adapted to be operated by pressure ranging from a. redetermined minimum to a predetermined maximum, a pressure tank, a sump tank, means for placing liquid in said sump tank, means for p acing air under pressure in said pressure tank, and means for pumping liquid from said sump tank into said pressure tank to build up the pressure to said maximum. 1

3. In a vehicle control system, devices adapted to be operated by pressure ranging from a predetermined minimum to a redetermined maximum, a pressure tank a sump tank, means for placing liquid'in said sump tank, means permitting overflow of said liquid during filling and venting of the tank during operation thereof, means for placing air under pressure in said pressure tank, the tank pressure being then at said minimum and means for pumping liquid from said sump tank into said pressure tank to build up the pressure to said maximum.

system for vehicles, runnin by a dif pump is operating but to relieve the same when the pum is stationary.

5. In a vehicle, running gear, a pump adapted to be driven from said running gear at a velocity proportional thereto, a system into which said pump circulates fluid to provide a. difl'erential ressure, means associated with said system or making use of a nondifierential pressure as well as said differential pressureand slip means associated with said'pump for provlding said non-difierential pressure when the pump is stationary.

6. In a vehicle, running ear, a pump adapted to be driven from sai running gear at a velocity proportional thereto, a system into which said pump circulates fluid to provide a differential ressure, means associated with saidsystem or making use of a nondiflerential pressure as well as said differential pressure, and sli means associated with said pump for providing said non-differential pressure when the ump is stationar said sli means including an adjustably throttle by-pass from the outlet to the inlet of said pump.

7. In a control system, a pressure tank, a sump tank, a pump adapted to withdraw fluid from said sump tank and deliver the same to said pressure tank and a bypass from the pump delivery to the inlet 0 t e same, and a pressure-controlled valve in said by-pass.

8. In a control system, a pressure tank, a sump tank, a pump adapted to withdraw fluid from said sump tank and deliver the same to said pressure tank and a b ass from the pump delivery to the inlet 0 t e same and a pressure-controlled valve in said b -pass, said valve relievin at a predetermine maximum pressure an closing to build up pressure in said pressure tank at a predetermined minimum.

9. In a vehicle control system, running ar, 9. pump driven by said running gear and aving an inlet and outlet, said pump while moving maintaining a difl'erential pressure between said outlet and inlet, brakes operable in connection with the running gear, means permittin a motorman to set said brakes under di erential ressure conditions, means for equalizing the 'fl'erential pressures when the pump has stopped, lpassenger-o erated means for controlling sai associated with said equalizin means permitting the passenger-operate means to set brakes an means said brakes rather than permitting the motorman to do so when the pressure is equalized and the passenger-operated means has set vehicle is substantially at a standstill, said passenger-operator means dominating said operators control for applying brakes under standstill conditions.

11. In brake-operating means for vehicles adapted to be operated by a motorman and by passengers, means permitting full braking control by the motorman when the vehicle is in substantial motion, said means permitting braking control by the passenger when the brakes are not set by the motorman under standstill conditions. i

12. In brake-operating means for vehicles adapted to be operated by a motorman and by passengers, means permitting full braking control by the motorman when the vehicle is in substantial motion, saidmeans permitting brake application by the passenger to the exclusion of application by the motorman when the vehicle is at a standstill, said means permitting said motorman to have full brake control under standstill conditions when there is no passenger controlling.

13. In a vehicle control system, a pum movable when the vehicle moves, outlet an inlet lines therefor, said pump maintaining difl'erential pressure in the outlet and inlet lines thereof when the pump is in motion and an extension from the source of pressure, automatic means blocking pressure passage to said extension under differential pressure conditions and permitting passage of pressure thereto under equalized pressure conditions and means associated with said pump of pressure, automatic/means blocking pressure passage to said extension under differential pressure conditions and permittin passage of pressure thereto under equalize pressure conditions, means associated with said pump for equalizing said pressure when the pump has stopped, a motormans brake valve adapted to be moved to set the brakes under all conditions and a passenger-operated valve adapted to be moved to set said brakes under equalized pressure conditions. 15. In a vehicle control system, a pum movable proportionally to the vehicle spee outlet and inlet lines therefor, said pump sure passage to said extension under difierential pressure conditions and permitting passage of pressure thereto under equalized pressure conditions, means associated with said pump for equalizing said pressure when the pump has stopped, a motormans brake valve adapted to be controlled to set the brakes under differential pressure conditions and a outlet and inlet lines therefor, said pump passenger-operated valve adapted to be controlled to set said brakes under equalized pressure conditions, said motormans valve receiving pressure directly from the source of pressure and said passenger-controlled valve receiving pressure indirectly therefrom by we of said automatic means.

16. a vehicle control system, a pump, means for operating said pump proportionally to the vehicle speed outlet and inlet lines for the pump, said pump providing differential line pressure when moving and equalized line pressure when stationary, means carrying a positive pressure connected into the outlet of the pump at all times, a manually operable motormans brake valve drawing upon said positive pressure, a passenger-operated valve drawing upon said pressure only when the inlet pressure is equalized therewith and means connecting the passenger-operated valve and the motorman-operated valve whereby the latter can be caused to be opened I to apply brakes by action of the former, in-

dependently of the motorman under said equalized pressure conditions.

17. In a vehicle control system, a-pump, means for operating said pump proportionally to the vehicle speed outlet and inlet lines for the pump, said ump providin differential line pressure w en moving an equalized line pressure when stationary, means carry ing a positive pressure connected into the outlet of the pump at all times, a manually operable motormans brake valve drawing upon said positive pressure, a passenger-operated valve drawing upon said ressure onl when the inlet pressure is equa ed therewith and means connecting the passenger-o erated valve and the motorman-operate valve whereby the latter is caused to be opened to appl brakes by action of the former indepen ently of the motorman under said equalized ressure conditions, a dead-man control associated with said connecting means between .the passenger-operated valve and the motorman-operated valve, a vehicle power circuit and means, efiective during emergency and when the vehicle stops, for opening the vehicle power circuit by said dead-mans control.

18. In a vehicle control system, a pump movable proportionally to the vehicle speed,

in motion and an extension from the source of pressure, automatic means blockin ressure passage to said extension under (1% pressure conditions and permitting passage of pressure thereto under equalized pressure conditions, means associated with said pump for equalizing said pressure when the pump has stopped, a motormans brake valve adapted to be controlled to set the brakes under all conditions and a passenger-operated valve adapted to be controlled to set said brakes under equalized pressure conditions, said motormans valve receiving pressure directly from said pressure source, said passengercontrolled valve receiving pressure indirectly therefrom by way of said automatic means and means for rendering the motormans valve Operative by the passenger under said equalized pressure conditions. 1

19. In a vehicle control system, a-pump, means for operating said pump when the vehicle moves, outlet and inlet lines for the pump, said pump providing differential line pressure when operated and equalized line pressure when stationary, means carrying a positive pressure connected into the outlet of the pump at all times, a manually operable motormans brake valve drawing upon said positive pressure, a passenger-operated valve drawing upon said pressure only when the inlet pressure is equalized therewith, and

means connecting the passenger-operated valve and the motorman-operated valve whereby the latter is caused to be opened to apply brakes by action of the former independently of the motorman under said equalized pressure conditions, a dead-man control associated with said connecting means between the passenger-operated valve and the motorman-operated valve 'a vehicle power circuit, means efl'ective during emergency and when the vehicle stops for opening the vehicle power circuit by said deadmans control, saidt-last-named means functioning also to set the brakes; I

20. In a vehicle, running gear, a pump associated with the running gear adapted to run proportionally therewith, said pump maintaining a difl'erential pressure when. running, means for equalizing the pressure when the pump is stationa controlled means adapted to be operate b pump, valve means contro ling flow to said controlled means and an automatic valve erential fluid from the controlling flow to said valve means, whereby the latter may be operated under differential pressure conditions but not under equalized pressure conditions and means for manually operating said valve means.

21. In a control system for vehicles, braking means, means permittin a motormans control of the brakes when t e vehicle is in motion, a dead-manscircuit adapted to apply 

